This invention relates to solving problems on photoreceptor drum axles used in Xerography and more specifically in the toner cartridge remanufacturing industry. This includes copiers, laser printers and facsimile machines which will be referred to throughout this text as imaging machines. However, it should be noted that the scope of this invention is not limited to imaging machines that use toner cartridges but includes all dry toner copiers, laser printers and facsimile machines.
CANON has designed an all-in-one cartridge as seen in U.S. Pat. No. 4,975,744, issued Dec. 4, 1990 and assigned to CANON. Several companies have used these cartridges in laser printers, copy machines and facsimile machines, each with the varying printer engines and a different nameplate. Originally, these cartridges were designed to be "disposable". However, after the first all-in-one toner cartridge was introduced, it did not take long before laser cartridge remanufacturers such as myself began remanufacturing these cartridges. These "disposable" cartridges were designed to function for only one cartridge cycle without remanufacturing. The remanufacturers had found certain components that needed replacement on a regular basis. In 1990, the first aftermarket photoreceptor drum became available for use in remanufacturing the all-in-one cartridge of the "SX" engine variety, the most popular printer cartridge from around 1987 through 1994 at the time of this writing. When the long-life photoreceptor drum became available, the entire remanufacturing industry turned around and gained great strength and began a huge growth surge
that still continues. In October 1993, HEWLETT-PACKARD, the largest seller of this printer engine using the all-in-one cartridge, entered the cartridge remanufacturing industry with the "Optiva" cartridge, further increasing the size as well as credibility of this relatively new industry. However, this relatively new industry grew from the all-in-one cartridge shortly after its debut. Before the introduction of the long-life drum, sometimes called the "superdrum" or "duradrum", the SX cartridge would last for around three cartridge remanufacturing cycles at best, since the actual useful life of the OEM drum was three cycles. However, the long-life drums got their names from the fact that they were designed to last for many remanufacturing cycles or recharges as they are sometimes called. Typically, the long life drum can last for ten or more such cycles, unlike the typical OEM(Original Equipment Manufacturer) drum. With the additional developments of drum coatings, originally designed for OEM drums, the long-life drum may last for many additional cycles. Some coatings, in theory, were designed to be dissolved and removed from over the drum surface every 1-3 cycles, so the drum life of the long-life drum almost seems limitless.
However, with photoreceptor drums lasting for many cycles, other components of the cartridge have a tendency to require greater durability, a better solution, or a greater life. Also, as the success of these cartridges has skyrocketed, the demand is for cartridges with longer cycles, so component improvements are significant. Therefore, avoiding natural problems with prevention means must also be implemented for cartridges of longer life both in longer cycle times and greater number of cycles. One good example is the drum axle used in imaging machines.
A typical cartridge uses a photoreceptor drum and has two drum axles, one at each end of the drum. In the normal case one of the two ends has a drum axle that also functions as an electrical contact for grounding the photoreceptor. The other end uses a drum axle that is simply in place for mechanical purposes without electrical application. It is this nonelectrical drum axle that is improved in this invention. The SX cartridge that was discussed has a specific problem that is not discernable without careful study. There are literally millions of these SX cartridges in the field. The device of this invention was designed around the defect of this SX cartridge so the cartridge will last longer. Rather than recommend a different printer (not SX) to customers, applicants have made a design that can improve these millions of defective cartridges reinforcing existing components with this invention.
The problem with the nonconductive drum axle is that the new ones are made of a plastic that is not wear resistant. This is interesting because the original drum axle was made of all steel. Eventually, the all metal drum axle was duplicated in plastic. The plastic versions are the majority of drum axles in the field at this time. However, the plastic axles become so worn that it can be seen by visual inspection with the naked eye.
The drum axle has an attach section and a shaft section. It is the shaft section that wears. When the shaft portion wears, its outside diameter decreases. It is this outside diameter that keeps the drum aligned with respect to its rotational axis. However, after the wear decreases this outside diameter, the drum is free to wobble. It wobbles, and will cause various photoreceptor drum operation defects. One defect that is visible on the output page is a light copy printed on the plastic drum axle side. As the problem gets worse with increased wear, eventually, in the most extreme case, the entire output page can be light or a completely white page can even be printed. The applicant had to do extensive research and development to fully understand the cause of the problem. Once the cause of the problem was discovered, a design was made to fix the problem and thus improve the drum axle.